Extruding / Scaling from reference edge (?)
If I'm understanding you correctly...
You want to create a sharp edge to your axe. The way I would achieve this is by using the Offset Edges which is now part of the Edit Mesh Tools addon.
First in object mode apply the scale (ctrl-a -&gt; Scale) (I removed half the axe for clarity)
In edit mode remove the faces around the perimeter of your axe, select both faces and do Edge -&gt; Bridge Edge Loops

Next add an edge loop to the centre of the new faces. ctrl-r -&gt; hover over the faces -&gt; left click -&gt; right click (drop the loop in the middle)

Then choose Edge -&gt; Offset Edges -&gt; Move and play around with the settings

You have a LOT of verices around the edge of your axe, so you will get some edges crossing over each other if you pull out the edges too far, but this is a whole other issue :)